According to Rogerroger here...
https://a2asimulations.com/forum/viewtopic.php?f=10&t=68079...'registry conflicts' prevent BoB1 and BoB2 from living happily together on the same hard drive, in the absence of some complicated jiggery-pokery, described in that post.
If that's not implicated, maybe patch to the most recent BDG update available for BoB1, and then try different combinations of settings for 2d resolution, 3d resolution and 'use desktop resolution' ticked or unticked (if indeed that BoB2 option is also available in BoB1).
Good luck!